Chimps use similar conceptual metaphors to the human "top of the tree" or "bottom of the pile" to map social and other hierarchies, new research has shown.
The argument goes that we humans use these sorts of phrases purely because we have language and this provides a mental framework into which we can slot social associations or other sequences.
This begs the question, what do other animals, that lack language, do?
Ikuma Adachi, from Kyoto University, writing in eLife, constructed a clever experiment involving chimpanzees to find out. The animals were trained to look at an image of another chimp that they may, or may not, recognise on a computer screen.
The first picture was removed and then two chimp pictures were presented, one above the other. If the animals recognised one of the two images as a chimp they'd seen immediately before, they pressed a button.
What was surprising is that if the individual they were looking for was someone they knew and was higher up the pecking order than them but was displayed lower down the screen, they took much longer to spot them than if they were shown at the top.
Conversely, lower socially-ranked animals displayed at the screen top were recognised more slowly than if they were presented below the other animal.
Clearly, the animals were looking on the screen at the place they thought should correspond to the social position of their peer: higher up for more senior animals and lower down for their subordinates.
This shows, says Ikuma, that actually the reason we use phrases like "top tier" and "bargain basement" is more a reflection on the way our brains work than anything to do with language.
We are putting into words where things and other individuals sit within the mental framework that we use to organise our view of the world. "Chimps are using the same framework," he says; and it probably evolved as a way to minimise the cognitive processing cost of organising and handling information.
We humans just happen to have the ability to say it how it is!